The metatarsus of the heterodontosaurid MPEF-PV 3826 is one of the smallest known for Ornithischia, and size estimation based on this specimen may reveal new frontiers regarding the smallest sizes reached in the lineage. Aiming to estimate the body size of MPEF-PV 3826 and present a conservative model for size estimation in fragmentary fossil specimens, several linear regressions were performed relating the length of hind limb bones with body length and sampling different species along all major ornithischian lineages. For each case, the variables were analysed using linear regressions of raw and logarithm-transformed datasets, excluding the obtained outliers and considering possible gait-related partitions. The best models were chosen based on their adjustment, their predictive capabilities, locomotor morphotypes and the possibility of hind limb preservation. The best model selected to estimate the body length of MPEF-PV 3826, based on metatarsal-III length, revealed a 430.68 mm long body, which is amongst the smallest known for Heterodontosauridae. Linear models can represent a useful tool for body length estimation based on hind limb measurements of fragmentary ornithischian specimens. MPEF-PV 3826, an active component of the paleocommunity rather than a hatchling individual, is hereby proposed to represent one of the smallest ornithischian specimens ever known, playing an important role in the understanding of the paleoecology of Early Jurassic faunas.

During paleontological surveys conducted in 2013 and 2014 in Quaternary deposits from the Gruta do Urso cave, Tocantins State, nine isolated teeth and five postcranial elements of Equus neogeus were recovered. Absolute datings indicate that E. neogeus inhabited the surroundings of Gruta do Urso cave during the Last Glacial Maximum. The specimens probably represent very young individuals that died outside the cave, were weathered prior to the final burial, with ontogenetic and taphonomic similarities. Herein, we report the first scavenger interaction of ursids and equids in the South American fossil record.

The early late Tremadocian (Tr2) interval is exceptionally well-represented in eastern areas of the Argentine Cordillera Oriental. New field collections and detailed taxonomic reassessments, as well as a reevaluation of regional data, permit the development of a highly resolved trilobite-based biostratigraphic framework. The concept of the traditional Bienvillia tetragonalis biozone is emended and the new Asaphellus nazarenensis biozone is proposed. Hence, the Tr2 interval encompasses a succession of four trilobite biozones including in ascending order the Kainella teiichii, the Bienvillia tetragonalis, the Asaphellus nazarenensis, and the Notopeltis orthometopa biozones. This resolution is notably higher than that provided by biostratigraphically significant groups such as graptolites and conodonts, and allows a detailed basinwide correlation. New taxonomic information on A. nazarenensis Tortello and Esteban and N. orthometopa (Harrington), is provided and the new species Asaphellus albae sp. nov. is defined. Detailed correlation of the trilobite fauna from the Tr2 interval with that of other paleocontinents is difficult. Taxa are mostly endemic or display wide geographic distributions but with long stratigraphic ranges. Overall, both trilobite-based and indirect international correlations highlight that this interval is hardly recognized, incompletely preserved, or the trilobite fauna is poorly known in most areas of Gondwana. Consequently, due to the completeness of the stratigraphic and fossil records of the Tr2 in the Cordillera Oriental, this region represents a global reference site for the study of this interval.

The Early Cretaceous marine deposits of the Agrio Formation are widely distributed in southern Mendoza and Neuquén provinces, Argentina. The stratigraphic distribution of upper Valanginian to upper Hauterivian organic-walled dinoflagellate cysts was evaluated at the Agrio Formation, at Bajada del Agrio locality. The assemblages exhibit a relatively moderate to low diversity and those with greater abundance are dominated by a small number of species such as Circulodinium distinctum, Cribroperidinium spp., Exochosphaeridium spp., Florentinia mantellii, Kiokansium unituberculatum, and Oligosphaeridium complex. Three diagnostic bioevents of lowest (LO) and highest (HO) stratigraphic occurrences of taxa calibrated with the local ammonoid zonation were identified for the Early Cretaceous of the Neuquén Basin: the LO of Callaiosphaeridium sp. (base of Holcoptychites neuquensis Zone, earliest Hauterivian), the LO of Cymososphaeridium validum (uppermost Hoplitocrioceras gentilii Zone, upper early Hauterivian) and the HO of Cymososphaeridium validum (lowermost Crioceratites diamantensis Zone, late Hauterivian). The studied assemblages are compared with Early Cretaceous assemblages from the Northern Hemisphere. In general, the association of dinoflagellate cysts together with the selected diagnostic species exhibit a clear affinity with those of the Mediterranean region.

Here we present a review of paleontology in Ecuador for the last three centuries, including the most significant studies, localities and their fossil record. This review is focused on four major fields of paleontology, which are: vertebrate paleontology, invertebrate paleontology, paleobotany and micropaleontology-palynology. The main fossil discoveries for each of these fields are ordered chronologically by date of publication and summarized in tables, maps and figures. Finally, we briefly discuss the current and near future challenges of paleontological research in the country.